Printing devices can rely on sensing sheets of paper to ensure they are properly processed. Conventional printing systems can utilize light sensors to detect the presence and/or location of a paper in a system. When the paper passes over a sensor, the light path is broken, signaling the presence of the paper.
Conventional printing devices are also known that utilize ultrasound for sensing paper features. In particular, an ultrasound speaker can issue a sound, and according to the attenuation of the signal, a number of sheets of paper can be determined.